And they were amazed at what they discovered while making "The Big Year": Bird-watchers, or "birders," hopping on planes, flitting from Attu, Alaska to Key West, trying to spot the rarest birds in North America during the course of a calendar year.

And the most amazing discovery of all? Honor.

"This huge competition, birders all over the country, is done on the honor system," Martin says. "I thought for sure you'd have to at least have a photograph. Then I thought, 'Photographs can be faked or bought anywhere.' It has to be done on the honor system. You have to admire that, because there is almost nothing in American society that operates on the honor system."

As author Mark Obmascik wrote in "The Big Year: A Tale of Man, Nature, and Fowl Obsession," the book on which the film is based, "In a Big Year, there are few rules and no referees."

Black pipes up: "It just seems like they're wide open and vulnerable to fraud, doing it that way. Someone could come and cheat, blow wide open the world record."

Then Wilson weighs in: "You know, they could verify it with travel, if it ever came to that. 'This rare bird was only spotted here at this time, so do you have the paperwork to show that you were there?'"

Martin remembers a line Wilson's character utters in the movie: "You know the one," he prompts Wilson. "'People know who cheats. Everyone knows' And you go, 'Who wants to be THAT guy?'"

Black, 42, Wilson, 42, and Martin, 66, decided to team up for this comedy about life priorities, obsessions and birding for reasons they can't quite explain. Was it their chemistry?

"I always feel that it's like when you're a kid and you're spending the night at a friend's house, and you assume it's going to be this GREAT time," Wilson says in that familiar tall-tale drawl. "And the moment you get there, you realize, 'Oh, I made a mistake. I don't want to be at this house. The house SMELLS weird. Their parents are going to give you chores!'"

Martin and Black are laughing so loudly the phone seems to go dead for a moment.

"That's what it's like with actors. I know RIGHT from the start, 'OK, this was a mistake. This is going to be tricky. I'm not necessarily simpatico with these guys.'"

OK, Wilson is joking, but it might not have been chemistry. So it must have been the travel, right? British Columbia and environs?

"The travel turned out to be a bonus, these gorgeous locations they took us to," Wilson says. "We weren't filming in Manhattan and going to the clubs every night. But we were sort of in the Yukon dodging grizzles, in Tofino, seeing bald eagles."

Tofino is that part of Vancouver Island "where people go in the fall to watch storms," Martin explains. "Very violent storms come in and these people go visit just to see the storms. It looks just like Attu, Alaska, don't you think?"

Actually, yes. Treeless, storm-swept and covered with birds. So if it wasn't chemistry OR travel, the trio must have done the movie for the birding.

"Since I was playing the record holder for having a Big Year, so going into it I had to get myself up to some of expert level," Wilson says. "We had experts helping us. But I just, uh, followed the script."

"What he's saying is NO. He didn't become an expert birder," Martin says, contradicting Wilson. "You really can't pick and choose your passions. I had never quite gotten the passion for this that my wife, for example, has. I'm not going to put on a parka and a pair of binoculars and a funny hat.

On the day of this interview, Martin has been named Bluegrass Entertainer of the Year, which is why he adds, "My passions are art [he's a well-known collector] and the five string banjo!"

Black, famously an indoor guy, chortles at the suggestion that he looks "at home with a pair of binoculars." But he's the one who left with the most appreciation for the allure of the sport.

"Before I read this script, I would look at birders and go, 'What are they DOING, wasting all this time with their binoculars, going all around to find this or that bird?' It looked easy, and it was easy to make fun of. … But when you get to know a couple of birders, you realize they're special. … Their brains are so attuned, their eyes and ears so obsessively sensitive to birds… I find that makes them sort of superhuman.

"You see this speck on the horizon and the dude next to you goes, 'Yup. That's a condor.' Wait. What? He could tell by the speed of the wing flapping that it was a condor. You're in awe."